Foundry core and binder therefor



Patented at. 14, 1939 i UNITED STATES mummy cons AND man s Omer 8. Smith, Rockford, 11L, assignmto Smith Oil & Refining Company, ,Rockford, Ill, a corporatlon of Illinois No Drawing Application April 29, 1987, erlal No. 189,716

5Claims. (cue-1st) W This invention relates to core binders and has special reference to liquid core binders known commonly as core oils and to cores made therefrom.

An important object of the invention is the provision of a generally improved core oil made from cheaper materials and having a lesser drying time than conventional oils, together with improved drying characteristics.

A further object of the invention is the provision of cores of generally improved properties including improved strength and a decreased tendency to produce smoke and gas when hot metal is poured thereagainst in the making of castings.

I have found that certain fatty acid constituents of oils of animals derivation having the general formula Canal-802, when present in core oils, impart thereto certain highly desiredproperties. The most common of the fatty acids belonging to this series are clupanodonic acid, isanic acid, and arachidonic acid,'of which the former is the most important. Clupanodonic acid, which is probably the most important member of the series, in the substantially pure state, is a pale yellow liquid having fishy odor and an iodine value (Wiis) of about 350. However, in its crude state it is commonly associated with isanic and arachidonic acids and other fatty acids. The emperical formula 02211240: is the commonly accepted formula.

I have foundthat each of these fatty acids and the mixture of the same asvfound in the crude clupanodonic acid produce core oils of exceptional merit. The crude acid has an iodine value of'about 225 or higher, depending upon the purity of the material, and because of its lower cost, I prefer to employ the crude form, though the pure acid or the other known members of this homologous series may be employed.

- In practicing the invention, the crude clupanodonic acid may be used as the sole binding ingredient of the core oil, or it may be used in combination with conventional ingredients as by being substituted for a part or all of the vegetable or other binding oil commonly used therein. For

example, I may prepare core oil by using 90% of crude clupanodonic acid and 10% of a solvent or so much of a solvent as may be necessary to produce an oil which does not stick to the core box. On the other hand, I may add a required amount, as for example 25% of the acid to a conventional core oil containing soy bean oil or 1 fish oil for the purpose of accelerating the drying thereof and to produce a corehaving greater strength. Considering all of the factors, such as price, drying speed required, core strength required, and other factors, I have found the 'following range to be preferable for the usual run of cores: 25 to 50% clupanodonic acid, 25 to 50% vegetable or other conventional oils, rosin, and thinner.

I have found that cores produced with clupanodonic acid develop considerably greater strength than cores from conventional core binders, that the strength is developed in a considerably shorter baking time, and at'lower baking temperatures, and that the amount of gas or smoke produced during the use of the cores is substantially less.

Byway of illustration of the manner in which the invention may be practiced and for purposes of comparison, the following table is'given, showing the manner in which various core oils develop their strength under baking:

30% 0. acid, 30% fish oil, 20% resin, 20% thinner 25% 0. acid, 26% fish oil, 25 a rosin Baked at 400 r.

- as tmimr stantially twice the strength of the specimen made with linseed oil. The strengths given in the table are those of a standard tensile strength briquet 1'! square made from a 1-40 mixture of lake sand having approximately 2% moisture. It willbe seen that the specimen made with clupanodonic acid reached a maximum strength of 251 after "I5 minutes of baking at 400 F., whereas the linseed oil and the fish oil specimens did not reach their maximum strength until minutes or later. It will also be seen. that the maximum strength of the clupanodonic acid specimen was considerably greater than the maximum strength of the linseed oil specimens in spite of the fact that the baking conditions were such as to favor the linseed oil specimens. Furthermore, from the last column it will be noted that by the use of 30% clupanodonic acid and 30% fish oil, specimens were produced having very nearly the-same average vmaximum strength as the specimens produced from straight linseed 011. Thus, by using clupanodonic acid in conjunction with the conventional vegetable or other binding oils of core binders, the-maximum strength is materially increased. Furthermore, it will be observed that the last mentioned core oil is considerably cheaper than straight linseed oil, since both the fish oil and the crude clupanodonic acid are cheaper than linseed oil.

The percentage of crude clupanodonic acid required to produce an appreciable effect upon the core strength and core drying properties will vary somewhat depending'upon the purity'of the materialv as indicated by the iodine value, but in general I find that a. minimum of about 25% of the total oil is required where the crude acid employed has an iodine value of 225 to 250. Somewhat smaller amounts may be employed where the iodine value of the crude acid is higher.

The relative properties of core oil and sand may vary widely as in conventional practice, though in-.general a smaller percentage of core on maybe employed than would be employed under like circumstances when a conventional core oil is used. My improved core oil may, of course, be used in conjunction with serial binders and other foundry aids, and requires no essential departure from conventional foundry practice with the exception of the baking time and temperatures.

While -I have thus described specific embodiments of the invention, numerous changes and alterations may be made therein within the spirit of the invention, and I do not wish to be limited except as required by the prior art -and the scope. of the appended claims, in which I claim:

1. A core oil comprising a highly unsaturated 10 fatty acid of the series having the general formula Gama-802 and a thinner therefor.

2. A core oil comprising clupanodonic acid and a thinner therefor.

3. A core 011 comprising 'clupanodonic acid, a binding agent, and a thinner.

4. A core oil comprising crude clupanodonic acid, a binding agent, and a thinner, the crude clupanodonic acid comprising more than about 25% of the mixture.

5. A baked foundry core comprising sand and a binder therefor including clupanodonic acid and a binding agent, wherein clupanodonic acid comprises at least 25% of the binder.

- OMER S.

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